Technology for transmitting a TDM signal via a network has been proposed (for example, see Patent Document 1). Examples of the above-described technology in the related art are structure-agnostic time division multiplexing over packet (SAToP) of Request for Comments (RFC) 4553, circuit emulation service over packet switched network (CESoPSN) of RFC 508, Metro Ethernet Forum 8 (MEF8), and the like. In these technologies, it is necessary to use a packet itself to restore a frequency component of a TDM signal because a packet network is asynchronous. Specifically, the restoration of the frequency component of the TDM signal is implemented by a method of inserting time information into a packet, a method of setting a packet transmission interval by a TDM frequency, or the like.
FIG. 7 illustrates an example of a system for transmitting a TDM signal via a packet network. In the example of FIG. 7, a transmitting device P10 includes a packet conversion unit P11, and a receiving device P20 includes a packet decoding unit P21, a clock reproduction unit P22, and a TDM signal restoration unit P23. The transmitting device P10 converts the TDM signal into packets, and transmits the packets to the receiving device P20 via the packet network PN. If the receiving device P20 receives the packets, the packet decoding unit P21 decodes the packets. In addition, the clock reproduction unit P22 generates a clock for restoring the TDM signal on the basis of the received packets (packets each including part of the TDM signal). The TDM signal restoration unit P23 restores the TDM signal on the basis of the clock generated by the clock reproduction unit P22.